I see you are in New York, which is not so far from me.
This winter I built an EGR valve tester that does not require the valve to be removed and measures sensor position vs current applied, and can surface intermittent valves. I hope, at the east coast maintenance event in June, to test a number of valves and see if there is a correlation between brand, age, etc. I think that the failure modes are gradual and include the sensor getting intermittent and one I don't think we've talked about: internal friction giving different values for the same position whether the valve is opening or closing. There is a fix for the intermittent sensor, but after doing it on mine, I retested it and found it getting "noisy" again.
Unless life stops me, I will also be attending the Ohio event in September and will bring my tester. It would be really cool to get measurements on a bunch of valves and characterize the different replacements available.
Please ask your mechanic to return your old valve to you, so that we can measure it sometime in the future. Perhaps write on the side of it the mileage when it was replaced.
2004 MT Red, 143K miles "new", ~160K now
2003 CVT Silver, 181K miles "new", 181K now